1. Field of the Invention
The present invention is directed generally to truss rods that are installable in necks of stringed musical instruments, such as guitars.
2. Description of the Related Art
Many stringed instruments (such as guitars, bases, cellos, violins, violas, and the like) have a body portion connected to a neck. The body portion and neck are typically constructed from wood. The neck may include a fingerboard on which a plurality of spaced apart frets may be distributed lengthwise. A plurality of stings are attached at one end to a distal portion (sometimes referred to as a “headstock” or “peg head”) of the neck, and at the other end to the body portion of the instrument. Tension is imparted into the strings (often by tuning pegs). Unfortunately, this tension may bend the neck such that the neck curves away from the strings (referred to herein as a “backward” direction). In other words, when viewed from the front, the neck may curve concavely.
A truss rod may be installed in the neck under the fingerboard to help counteract the tension on the neck imparted by strings (or other external forces) and prevent the neck from bending. Thus, the truss rod may help maintain a desired amount of curvature (or relief) in the neck.
As a stringed instrument (e.g., a guitar) ages or is played, the wood shifts, warps, expands, contracts, and/or flexes. This movement may cause changes in the curvature of the neck. In some cases, the curvature in the neck may be adjusted to some extent by adjusting the truss rod. However, the adjustment options provided by many prior art truss rods are limited and may not be sufficient to adjust the neck into a desired shape.
For example, many prior art truss rods are configured to adjust the curvature of the neck along only a single direction (e.g., in a direction toward the strings, referred to herein as a “forward” direction). Such truss rods are commonly referred to as “single action” truss rods. Single action truss rods are effective only when the neck is bent in a direction opposite the single direction in which the truss rod is configured to adjust the curvature of the neck. Unfortunately, the neck may be bent in any direction, including toward the strings (the “forward” direction), away from the strings (the “backward” direction), sideways in a first direction (referred to herein as a “right” direction), and/or sideways in a second direction (referred to herein as a “left” direction) that is opposite the right direction. The terms “forward,” “backward,” “right,” and “left” have been assigned arbitrarily for the purposes of describing the bending of the neck of the instrument. As is apparent to those of ordinary skill in the art, the neck may be bent in a single direction, more than one direction, and/or twisted.
A “double action” truss rod is configured to bend the neck in two directions (e.g., the forward and backward directions). Although some double action truss rods are currently available, they bend only in the middle and only in an arc-like shape. Thus, they cannot be adjusted at a specific fret along the neck of the instrument. In addition, these prior art double action truss rods are not configured to hold the neck straight with respect to the right and/or left directions. For example, many conventional truss rods have a round cross-sectional shape that allows them to rotate inside the neck of an instrument. Such “double action” truss rods allow the neck to twist and/or bend in the right and/or left directions, which may permanently ruin the instrument. This type of failure may occur during the manufacturing phase or during the life of the instrument. Further, prior art double action truss rods are both bulky and heavy, which adds undesirable weight to musical instruments. Increased weight negatively affects the playability of an instrument.
Therefore, a need exists for new double action truss rod designs. Lighter weight, less bulky truss rods would be particularly desirable. Truss rods configured to hold the neck straight in the right and left directions are also desirable. The present application provides these and other advantages as will be apparent from the following detailed description and accompanying figures.